(CNN) -- The American Civil Liberties Union has filed a lawsuit in Pennsylvania challenging the state's ban on same-sex marriages and its refusal to recognize such marriages from other states.

A similar suit will be filed in Virginia, while an existing lawsuit in North Carolina will be amended to broaden the scope, the ACLU said Tuesday.

"The Pennsylvania lawsuit alleges that the state's Defense of Marriage Act and refusal to marry lesbian and gay couples or recognize their out-of-state marriages violates the fundamental right to marry, as well as the Equal Protection Clause of the Fourteenth Amendment," the ACLU said in a statement.

The move comes on the heels of the Supreme Court decision that struck down a key part of the federal Defense of Marriage Act last month. In a separate ruling, the high court also cleared the way for same-sex marriages in California to resume.

"Our goal is at least 20 states with the freedom to marry by the end of 2016," the ACLU said on its website. The group plans to achieve its goal through litigation, lobbying and ballot campaigns. The organization also plans to reach out to "right-of-center" voices and has hired Republican strategists to do so.